#ifndef INCLUDES_TARANTOOL_BOX_VY_CACHE_H
#define INCLUDES_TARANTOOL_BOX_VY_CACHE_H
/*
 * Copyright 2010-2017, Tarantool AUTHORS, please see AUTHORS file.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the
 *    following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdint.h>
#include <stdbool.h>

#include <small/rlist.h>

#include "iterator_type.h"
#include "vy_stmt.h" /* for comparators */
#include "vy_read_view.h"
#include "vy_stat.h"
#include "small/mempool.h"

#if defined(__cplusplus)
extern "C" {
#endif /* defined(__cplusplus) */

struct vy_history;

/**
 * A record in tuple cache
 */
struct vy_cache_entry {
	/* Cache */
	struct vy_cache *cache;
	/* Statement in cache */
	struct tuple *stmt;
	/* Link in LRU list */
	struct rlist in_lru;
	/* VY_CACHE_LEFT_LINKED and/or VY_CACHE_RIGHT_LINKED, see
	 * description of them for more information */
	uint32_t flags;
	/* Number of parts in key when the value was the first in EQ search */
	uint8_t left_boundary_level;
	/* Number of parts in key when the value was the last in EQ search */
	uint8_t right_boundary_level;
};

/**
 * Internal comparator (1) for BPS tree.
 */
static inline int
vy_cache_tree_cmp(struct vy_cache_entry *a,
		  struct vy_cache_entry *b, struct key_def *cmp_def)
{
	return vy_tuple_compare(a->stmt, b->stmt, cmp_def);
}

/**
 * Internal comparator (2) for BPS tree.
 */
static inline int
vy_cache_tree_key_cmp(struct vy_cache_entry *a,
		      const struct tuple *b, struct key_def *cmp_def)
{
	return vy_stmt_compare(a->stmt, b, cmp_def);
}

#define VY_CACHE_TREE_EXTENT_SIZE (16 * 1024)

#define BPS_TREE_NAME vy_cache_tree
#define BPS_TREE_BLOCK_SIZE 512
#define BPS_TREE_EXTENT_SIZE VY_CACHE_TREE_EXTENT_SIZE
#define BPS_TREE_COMPARE(a, b, cmp_def) vy_cache_tree_cmp(a, b, cmp_def)
#define BPS_TREE_COMPARE_KEY(a, b, cmp_def) vy_cache_tree_key_cmp(a, b, cmp_def)
#define bps_tree_elem_t struct vy_cache_entry *
#define bps_tree_key_t const struct tuple *
#define bps_tree_arg_t struct key_def *
#define BPS_TREE_NO_DEBUG

#include "salad/bps_tree.h"

#undef BPS_TREE_NAME
#undef BPS_TREE_BLOCK_SIZE
#undef BPS_TREE_EXTENT_SIZE
#undef BPS_TREE_COMPARE
#undef BPS_TREE_COMPARE_KEY
#undef bps_tree_elem_t
#undef bps_tree_key_t
#undef bps_tree_arg_t
#undef BPS_TREE_NO_DEBUG

/**
 * Environment of the cache
 */
struct vy_cache_env {
	/** Common LRU list of read cache. The first element is the newest */
	struct rlist cache_lru;
	/** Common mempool for vy_cache_entry struct */
	struct mempool cache_entry_mempool;
	/** Size of memory occupied by cached tuples */
	size_t mem_used;
	/** Max memory size that can be used for cache */
	size_t mem_quota;
};

/**
 * Initialize common cache environment.
 * @param e - the environment.
 * @param slab_cache - source of memory.
 */
void
vy_cache_env_create(struct vy_cache_env *env, struct slab_cache *slab_cache);

/**
 * Destroy and free resources of cache environment.
 * @param e - the environment.
 */
void
vy_cache_env_destroy(struct vy_cache_env *e);

/**
 * Set memory limit for the cache.
 * @param e - the environment.
 * @param quota - memory limit for the cache.
 *
 * This function blocks until it manages to free enough memory
 * to fit in the new limit.
 */
void
vy_cache_env_set_quota(struct vy_cache_env *e, size_t quota);

/**
 * Tuple cache (of one particular LSM tree)
 */
struct vy_cache {
	/**
	 * Key definition for tuple comparison, includes primary
	 * key parts
	 */
	struct key_def *cmp_def;
	/** Set if this cache is for a primary index. */
	bool is_primary;
	/* Tree of cache entries */
	struct vy_cache_tree cache_tree;
	/* The vesrion of state of cache_tree. Increments on every change */
	uint32_t version;
	/* Saved pointer to common cache environment */
	struct vy_cache_env *env;
	/* Cache statistics. */
	struct vy_cache_stat stat;
};

/**
 * Allocate and initialize tuple cache.
 * @param env - pointer to common cache environment.
 * @param cmp_def - key definition for tuple comparison.
 * @param is_primary - set if cache is for primary index
 */
void
vy_cache_create(struct vy_cache *cache, struct vy_cache_env *env,
		struct key_def *cmp_def, bool is_primary);

/**
 * Destroy and deallocate tuple cache.
 * @param cache - pointer to tuple cache to destroy.
 */
void
vy_cache_destroy(struct vy_cache *cache);

/**
 * Add a value to the cache. Can be used only if the reader read the latest
 * data (vlsn = INT64_MAX).
 * @param cache - pointer to tuple cache.
 * @param stmt - statement that was recently read and should be added to the
 * cache.
 * @param prev_stmt - previous statement that was read by the reader in one
 * sequence (by one iterator).
 * @param direction - direction in which the reader (iterator) observes data,
 *  +1 - forward, -1 - backward.
 */
void
vy_cache_add(struct vy_cache *cache, struct tuple *stmt,
	     struct tuple *prev_stmt, const struct tuple *key,
	     enum iterator_type order);

/**
 * Find value in cache.
 * @return A tuple equal to key or NULL if not found.
 */
struct tuple *
vy_cache_get(struct vy_cache *cache, const struct tuple *key);

/**
 * Invalidate possibly cached value due to its overwriting
 * @param cache - pointer to tuple cache.
 * @param stmt - overwritten statement.
 * @param[out] deleted - If not NULL, then is set to deleted
 *             statement.
 */
void
vy_cache_on_write(struct vy_cache *cache, const struct tuple *stmt,
		  struct tuple **deleted);


/**
 * Cache iterator
 */
struct vy_cache_iterator {
	/* The cache */
	struct vy_cache *cache;

	/**
	 * Iterator type, that specifies direction, start position and stop
	 * criteria if the key is not specified, GT and EQ are changed to
	 * GE, LT to LE for beauty.
	 */
	enum iterator_type iterator_type;
	/* Search key data in terms of vinyl, vy_stmt_compare argument */
	const struct tuple *key;
	/* LSN visibility, iterator shows values with lsn <= vlsn */
	const struct vy_read_view **read_view;

	/* State of iterator */
	/* Current position in tree */
	struct vy_cache_tree_iterator curr_pos;
	/* stmt in current position in tree */
	struct tuple *curr_stmt;

	/* Last version of cache */
	uint32_t version;
	/* Is false until first .._get or .._next_.. method is called */
	bool search_started;
};

/**
 * Open an iterator over cache.
 * @param itr - iterator to open.
 * @param cache - the cache.
 * @param iterator_type - iterator type (EQ, GT, GE, LT, LE or ALL)
 * @param key - search key data in terms of vinyl, vy_stmt_compare argument
 * @param vlsn - LSN visibility, iterator shows values with lsn <= vlsn
 */
void
vy_cache_iterator_open(struct vy_cache_iterator *itr, struct vy_cache *cache,
		       enum iterator_type iterator_type,
		       const struct tuple *key, const struct vy_read_view **rv);

/**
 * Advance a cache iterator to the next key.
 * The key history is returned in @history (empty if EOF).
 * @stop flag is set if a chain was found in the cache
 * and so there shouldn't be statements preceding the
 * returned statement in memory or on disk. The function
 * returns 0 on success, -1 on memory allocation error.
 */
NODISCARD int
vy_cache_iterator_next(struct vy_cache_iterator *itr,
		       struct vy_history *history, bool *stop);

/**
 * Advance a cache iterator to the key following @last_stmt.
 * The key history is returned in @history (empty if EOF).
 * Returns 0 on success, -1 on memory allocation error.
 */
NODISCARD int
vy_cache_iterator_skip(struct vy_cache_iterator *itr,
		       const struct tuple *last_stmt,
		       struct vy_history *history, bool *stop);

/**
 * Check if a cache iterator was invalidated and needs to be restored.
 * If it does, set the iterator position to the first key following
 * @last_stmt and return 1, otherwise return 0. Returns -1 on memory
 * allocation error.
 */
NODISCARD int
vy_cache_iterator_restore(struct vy_cache_iterator *itr,
			  const struct tuple *last_stmt,
			  struct vy_history *history, bool *stop);

/**
 * Close a cache iterator.
 */
void
vy_cache_iterator_close(struct vy_cache_iterator *itr);

#if defined(__cplusplus)
} /* extern "C" { */
#endif /* defined(__cplusplus) */

#endif /* INCLUDES_TARANTOOL_BOX_VY_CACHE_H */
